DESCRIPTION

netlink.h
defines several standard macros to access or create a netlink datagram.
They are similar in spirit to the macros defined in
cmsg(3)
for auxiliary data. The buffer passed to and from a netlink socket should
be only accessed using these macros.

NLMSG_ALIGN

Round the length of a netlink message up to align it properly.

NLMSG_LENGTH

Gets the payload length as argument and returns the aligned length to store
in the
nlmsg_len
field of the
nlmsghdr.

NLMSG_SPACE

Return the number of bytes a netlink message with payload of the passed length
would occupy.

NLMSG_DATA

Return a pointer to the payload associated with the passed
nlmsghdr.

NLMSG_NEXT
Get the next
nlmsghdr
in a multipart message. The caller must check if the current nlmsghdr
didn't have the NLMSG_DONE set - this function doesn't return NULL on end. The
length parameter is an lvalue containing the remaining length of the message
buffer. This macro decrements it by the length of the message header.

NLMSG_OK

Return true if the netlink message is not truncated and ok to parse.

NLMSG_PAYLOAD

Return the length of the payload associated with the
nlmsghdr.

NOTES

It is often better to use netlink via
libnetlink
than via the low level kernel interface.